Question

Study the data of the following three categories A. B and C.

Category	Name of the element	Atomic Mass
A	Li	7
	Na	23
	K	39
B	N	14
	P	31
	As	74
C	B	10.8
	Al	27
	Ga	69.7

1. From the given three categories A, B and C, pick the one which forms Dobereiner’s Triads.
2. Why did Mendeleev placed elements of category A, B and C in three different groups?
3. Is Newland law of octaves applicable to all the three categories?

Give reason to justify your answer.

Answer 1

1. Category A (Li Na K) show Dobereiner’s triads.
2. Mendeleev categorised the elements according to similar chemical properties and placed them in ascending order of atomic mass. Despite having distinct chemical characteristics, the elements in A, B, and C are comparable to one another.
3. No, the Newland Law of Octaves does not apply since each of the three categories’ eighth elements will not exhibit the same property as the first. Furthermore, the Newland Octaves law only applies to calcium.